mac80211: remove sta->last_ack_signal

This file only feeds a debugfs file that isn't very useful, so remove
it. If necessary, we can add other ways to get this information, for
example in the NL80211_CMD_PROBE_CLIENT response.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/debugfs_sta.c

@@ -50,7 +50,6 @@ static const struct file_operations sta_ ##name## _ops = {		\
 		STA_OPS(name)
 
 STA_FILE(aid, sta.aid, D);
-STA_FILE(last_ack_signal, last_ack_signal, D);
 
 static ssize_t sta_flags_read(struct file *file, char __user *userbuf,
 			      size_t count, loff_t *ppos)
@@ -366,7 +365,6 @@ void ieee80211_sta_debugfs_add(struct sta_info *sta)
 	DEBUGFS_ADD(agg_status);
 	DEBUGFS_ADD(ht_capa);
 	DEBUGFS_ADD(vht_capa);
-	DEBUGFS_ADD(last_ack_signal);
 
 	DEBUGFS_ADD_COUNTER(rx_duplicates, num_duplicates);
 	DEBUGFS_ADD_COUNTER(rx_fragments, rx_fragments);

net/mac80211/sta_info.h

@@ -373,7 +373,6 @@ DECLARE_EWMA(signal, 1024, 8)
  * @rx_dropped: number of dropped MPDUs from this STA
  * @last_signal: signal of last received frame from this STA
  * @avg_signal: moving average of signal of received frames from this STA
- * @last_ack_signal: signal of last received Ack frame from this STA
  * @last_seq_ctrl: last received seq/frag number from this STA (per TID
  *	plus one for non-QoS frames)
  * @tx_filtered_count: number of frames the hardware filtered for this STA
@@ -467,7 +466,6 @@ struct sta_info {
 	unsigned long rx_dropped;
 	int last_signal;
 	struct ewma_signal avg_signal;
-	int last_ack_signal;
 
 	u8 chains;
 	s8 chain_signal_last[IEEE80211_MAX_CHAINS];

net/mac80211/status.c

@@ -863,9 +863,6 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
 				ieee80211_lost_packet(sta, info);
 			}
 		}
-
-		if (acked)
-			sta->last_ack_signal = info->status.ack_signal;
 	}
 
 	rcu_read_unlock();